Sci-Fi Tech writes about Megaphone, a company that turns mobile phones into controllers for games that run in public spaces on large screens. Call in a number to join the game, then control your piece of action by punching buttons on the dialpad or by simply barking out orders.

I've played a game of Battle Tanks this way at a demo by LocaModa, another company that develops interesting mobile apps. Lots of fun. Would probably work well for movie theaters, too.